On the measurement of reinforcement frequency in the study of preference

In a two-link, concurrent-chain schedule, pigeons' pecks on each key during the initial link occasionally produced a terminal link, during which only that key was operative. Responses in the terminal link were reinforced with food on either fixed-interval or variable-interval schedules. In one experiment, relative amount of responding in the initial link equaled the relative harmonic rate of reinforcement in the terminal links. In a second experiment, the selection of interreinforcement intervals in variable-interval schedules in the terminal links was such that rates of reinforcement based on the harmonic or on the arithmetic means of the interreinforcement intervals predicted opposite preferences in the initial links. The observed preference was consistent with that predicted by the harmonic rather than by the arithmetic rates of reinforcement.     

Stability criteria

Three approaches to the determination of behavioral stability were examined. In the first, a learning curve was fit to acquisition data (from Cumming and Schoenfeld, 1960), and the “experiment” stopped when the data approached sufficiently close to the theoretical asymptote. In the second, the data were analyzed for variability and linear and quadratic trend. In the third, the experiment was stopped when the magnitude of the daily changes in the data fell below a criterion. Accuracy was measured as deviation between the average value of the dependent variable when the experiment was stopped, and the average value over the last 100 sessions. The first approach was most accurate, but at the cost of requiring the most sessions and being the most difficult to apply. Both the second and third approaches provided acceptable criteria with a reasonable cost-accuracy tradeoff. The second approach permits a continuous adjustment of the criteria to accommodate the variability intrinsic in the experimental paradigm. The third, nomothetic, approach also takes into account the decreasing marginal utility of extended training sessions.     

Competing schools or stylistic variation in careers guidance interviewing

We know very little about how careers officers conduct careers guidance interviews. Research was carried out to discover how careers officers view interviewing, the factors that lead them to vary their interview style, and how they modify their approach with experience. There was little evidence that officers vary their style by using radically opposed models in different circumstances. Instead, variations in approach are best regarded as different combinations of ideas and techniques. Careers officers adapted their interview styles largely in response to the perceived needs of clients. Initial training course attended appeared to have a limited but enduring effect on interview style, but there was also evidence that with experience careers officers develop more confidence, coherence and flexibility. Careers officers judged their interviews to be most effective when they were able to establish a rapport with the client, to spend time drawing up a contract, to challenge clients in a sensitive way, and to structure the interview appropriately.     

The effect of timeout on performance on a variable-interval schedule of electric-shock presentation

Responding was maintained in squirrel monkeys under variable-interval schedules of electric shock presentation when a period of timeout followed each response-dependent shock. Response rate decreased when timeout duration was decreased, and responding ceased when timeout was eliminated. These results indicate that under certain conditions, a shock-free period following each response-produced shock is necessary to maintain responding.     

The kinematics of locomotion toward a goal

A mathematical model is developed that treats rats in runways as uniformly accelerated bodies. The purpose of the model is to permit conversion of the continuously varying measures of runway speeds at different points in the alley into three invariant parameters of performance: start latency, acceleration, and brakepoint. This simple model fits most of the data examined, and changes in the parameters throw new light on phenomena such as the partial reinforcement acquisition effect. In particular, it is shown that partially reinforced rats accelerate faster but cease accelerating earlier in the runway than do continuously reinforced rats. This explains the qualitative differences often found between start and goal speed measures. The analysis takes as its unit patterns of terminal behavior rather than the rate of the responses that constitutes them, and thus may permit coherent treatment of instrumental and operant behavior.     

Modeling modeling

Models are tools; they need to fit both the hand and the task. Presence or absence of a feature such as a pacemaker or a cascade is not in itself good. Or bad. Criteria for model evaluation involve benefit-cost ratios, with the numerator a function of the range of phenomena explained, goodness of fit, consistency with other nearby models, and intangibles such as beauty. The denominator is a function of complexity, the number of phenomena that must be ignored, and the effort necessary to incorporate the model into one's parlance. Neither part of the ratio can yet be evaluated for MTS, whose authors provide some cogent challenges to SET.     

Is guidance an applied science?: The role of theory in the careers guidance interview

Some of the findings of a study investigating careers officers' use of theoretical models in the careers guidance interview are discussed. Data were collected through visits to institutions offering Diploma in Careers Guidance courses, a large-scale questionnaire survey of careers officers, and semi-structured interviews and group discussions. There was evidence that in initial training, theory is used to support, rather than determine, the development of skills. Results also suggested that practising careers officers are familiar with a fairly wide range of theories, although in their interviewing they tend to apply broad principles of theory, rather than specific elements. Careers officers who trained some time ago were less familiar with theories than were those who trained more recently, and there was no support for the hypothesis that long service leads to a greater recognition of the relevance of theories generally. Familiarity with guidance and counselling theories appears to be more influential than knowledge of career theories on the way careers officers think about interviewing. Overall, the findings cast doubt on the view that careers guidance is an applied science.